Liquid crystal composition and liquid crystal display device

ABSTRACT

A liquid crystal composition is provided that satisfies at least one of the characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of a nematic phase, a small viscosity, a large optical anisotropy, a large dielectric anisotropy, a large specific resistance, a high stability to ultraviolet light and a high stability to heat, or is properly balanced regarding at least two characteristics. An AM device is provided that has a short response time, a large voltage holding ratio, a large contrast ratio, a long service life and so forth. The liquid crystal composition having a negative dielectric anisotropy contains a first component having especially negatively large dielectric, a second component having a large negative dielectric anisotropy and a low minimum temperature, a third component having a high maximum temperature or a small viscosity. The liquid crystal display device contains the liquid crystal composition.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a liquid crystal composition suitable for usein an active matrix (AM) device, and an AM device containing thecomposition. More specifically, the invention relates to a liquidcrystal composition having a negative dielectric anisotropy, and alsorelates to a device of an in plane switching (IPS) mode, a verticalalignment (VA) mode or a polymer sustained alignment (PSA) modecontaining the composition.

2. Related Art

In a liquid crystal display device, classification based on an operatingmode of liquid crystals includes phase change (PC), twisted nematic(TN), super twisted nematic (STN), electrically controlled birefringence(ECB), optically compensated bend (OCB), in-plane switching (IPS),vertical alignment (VA), polymer sustained alignment (PSA) and so forth.Classification based on a driving mode of the device includes a passivematrix (PM) and an active matrix (AM). PM is further classified intostatic, multiplex and so forth, and AM is classified into a thin filmtransistor (TFT), a metal insulator metal (MIM) and so forth. TFT isfurther classified into amorphous silicon and polycrystal silicon. Thelatter is classified into a high temperature type and a low temperaturetype according to a production process. Classification based on a lightsource includes a reflection type utilizing a natural light, atransmission type utilizing a backlight and a semi-transmission typeutilizing both the natural light and the backlight.

These devices contain a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to obtainan AM device having good general characteristics. Table 1 belowsummarizes a relationship between the general characteristics of thetwo. The general characteristics of the composition will be explainedfurther based on a commercially available AM device. A temperature rangeof a nematic phase relates to the temperature range in which the devicecan be used. A desirable maximum temperature of the nematic phase is 70°C. or more and a desirable minimum temperature is −10° C. or less. Theviscosity of the composition relates to the response time of the device.The rotation viscosity of the composition also relates to the responsetime of the device. A short response time is desirable for displaying amoving image. Accordingly, a small viscosity of the composition isdesirable. A small viscosity at a low temperature is more desirable.

TABLE 1 General Characteristics of Liquid Crystal Composition and AMDevice General Characteristics of a General No CompositionCharacteristics of an AM Device 1 Temperature range of a nematic Usabletemperature range is wide phase is wide 2 Viscosity is small¹⁾ Responsetime is short 3 Optical anisotropy is suitable Contrast ratio is large 4Dielectric anisotropy is Threshold voltage is low, electric positivelyor negatively large power consumption is small, and contrast ratio islarge 5 Specific resistance is large Voltage holding ratio is large, anda contrast ratio is large 6 It is stable to ultraviolet light Servicelife is long and heat ¹⁾A liquid crystal composition can be injectedinto a cell in a shorter period of time.

The optical anisotropy of the composition relates to the contrast ratioof the device. A product (Δn×d) of the optical anisotropy (Δn) of thecomposition and the cell gap (d) of the device is designed to maximizethe contrast ratio. A suitable value of the product depends on the kindof operation mode. In a device having a VA mode, a suitable value is ina range of from 0.30 μm to 0.40 μm, and in a device having an IPS mode,a suitable value is in a range of from 0.20 μm to 0.30 μm. In this case,a composition having a large optical anisotropy is desirable for adevice having a small cell gap. A large dielectric anisotropy of thecomposition contributes to a low threshold voltage, a small electricpower consumption and a large contrast ratio of the device. Accordingly,a large dielectric anisotropy is desirable. A large specific resistanceof the composition contributes to a large voltage holding ratio and alarge contrast ratio of the device. Accordingly, a composition having alarge specific resistance is desirable at room temperature and also at ahigh temperature in the initial stage. A composition having a largespecific resistance is desirable at room temperature and also at a hightemperature after it has been used for a long time. A stability of thecomposition to an ultraviolet light and heat relates to a service lifeof the liquid crystal display device. In the case where the stability ishigh, the device has a long service life. These characteristics aredesirable for an AM device used in a liquid crystal projector, a liquidcrystal television and so forth.

In an AM device having a TN mode, a composition having a positivedielectric anisotropy is used. In an AM device having a VA mode, acomposition having a negative dielectric anisotropy is used. In an AMdevice having an IPS mode, a composition having a positive or negativedielectric anisotropy is used. In an AM device having a PSA mode, acomposition having a positive or negative dielectric anisotropy is used.Examples of the liquid crystal composition having a negative dielectricanisotropy are disclosed in the following documents:

No. 1: JP 2005-35986 A

No. 2: JP 2005-105132 A

No. 3: JP 2005-281560 A

No. 4: JP 2005-290349 A

No. 5: WO 2006-040009 A

No. 6: JP 2007-254583A.

A desirable AM device is characterized as having a wide usabletemperature range, a short response time, a high contrast ratio, a lowthreshold voltage, a large voltage holding ratio, a long service life,and so forth. Even one millisecond shorter response time is desirable.Thus, a composition having characteristics such as a high maximumtemperature of a nematic phase, a low minimum temperature of a nematicphase, a low viscosity, a large optical anisotropy, a large dielectricanisotropy, a small pretilt angle, a large specific resistance, a highstability to ultraviolet light, a high stability to heat, and so forthis especially desirable.

One of the object of the invention is to provide a liquid crystalcomposition that satisfies at least one characteristic among thecharacteristics such as a high maximum temperature of a nematic phase, alow minimum temperature of a nematic phase, a small viscosity, a largeoptical anisotropy, a large dielectric anisotropy, a large specificresistance, a high stability to ultraviolet light and a high stabilityto heat and so forth. Another object of the invention is to provide aliquid crystal composition that is properly balanced regarding at leasttwo characteristics among many characteristics. Another advantage of theinvention is to provide a liquid crystal display device that containsthe liquid crystal composition. Another of the object of the inventionis to provide a liquid crystal composition that has a large opticalanisotropy, a large dielectric anisotropy, a high stability toultraviolet light and so forth, and is to provide an AM device that hasa short response time, a large voltage holding ratio, a large contrastratio, a long service life and so forth.

SUMMARY OF THE INVENTION

The invention concerns a liquid crystal composition having a negativedielectric anisotropy that includes three components, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formula (1), the second component is at least onecompound selected from the group of compounds represented by formula(2), and the third component is at least one compound selected from thegroup of compounds represented by formula (3):

wherein R¹, R², R⁴, R⁵ and R⁶ are each independently alkyl having 1 to12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons or alkenyl having 2 to 12 carbons in which arbitrary hydrogen isreplaced by fluorine; R³ is alkenyl having 2 to 12 carbons; ring A, ringB and ring C are each independently 1,4-cyclohexylene or 1,4-phenylene;ring D and ring E are each independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene, or 2,5-difluoro-1,4-phenylene; Z¹and Z² are each independently a single bond, ethylene, methyleneoxy orcarbonyloxy; and m and n are each independently 1, 2 or 3; p and q areeach independently 0, 1, 2 or 3; and the sum of p and q is 3 or less.

The invention also concerns a liquid crystal display device thatincludes the liquid crystal composition, and so forth.

One of the advantages of the invention is to provide a liquid crystalcomposition that satisfies at least one characteristic among thecharacteristics such as a high maximum temperature of a nematic phase, alow minimum temperature of a nematic phase, a small viscosity, a largeoptical anisotropy, a large dielectric anisotropy, a large specificresistance, a high stability to ultraviolet light and a high stabilityto heat and so forth. Another advantage of the invention is to provide aliquid crystal composition that is properly balanced regarding at leasttwo characteristics among many characteristics. Another advantage of theinvention is to provide a liquid crystal display device that containsthe liquid crystal composition. Another of the advantage of theinvention is to provide a liquid crystal composition that has a largeoptical anisotropy, a large dielectric anisotropy, a high stability toultraviolet light and so forth, and is to provide an AM device that hasa short response time, a large voltage holding ratio, a large contrastratio, a long service life and so forth.

DETAILED DESCRIPTION OF THE INVENTION

The terms used in the specification and claims are defined as follows.The liquid crystal composition and/or the liquid crystal display deviceof the invention may occasionally be expressed simply as “thecomposition” or “the device,” respectively. A liquid crystal displaydevice is a generic term for a liquid crystal display panel and a liquidcrystal display module. The “liquid crystal compound” is a generic termfor a compound having a liquid crystal phase such as a nematic phase, asmectic phase and so forth, and also for a compound having no liquidcrystal phase but being useful as a component of a composition. Theuseful compound contains, for example, a 6-membered ring such as1,4-cyclohexylene and 1,4-phenylene, and a rod like molecular structure.An optically active compound or a polymerizable compound mayoccasionally be added to the composition. Even in the case where thecompound is a liquid crystal compound, the compound is classified intoan additive. At least one compound selected from a group of compoundsrepresented by formula (1) may be abbreviated to “the compound (1).” The“compound (1)” means one compound or two or more compounds representedby formula (1). The other formulas are applied with the same rules.“Arbitrary” is used not only in cases when the position is arbitrary butalso in cases when the number is arbitrary. However, it is not used incases when the number is 0 (zero).

A higher limit of a temperature range of a nematic phase may beabbreviated to “a maximum temperature.” A lower limit of a temperaturerange of a nematic phase may be abbreviated to “a minimum temperature.”“A specific resistance is large” means that the composition has a largespecific resistance at room temperature and also nearly at the maximumtemperature of a nematic phase in the initial stage, the composition hasa large specific resistance at room temperature and also nearly at themaximum temperature of a nematic phase even after it has been used for along time. “A voltage holding ratio is large” means that a device has alarge voltage holding ratio at room temperature and also nearly at themaximum temperature of a nematic phase in the initial stage, the devicehas a large voltage holding ratio at room temperature and also nearly atthe maximum temperature of a nematic phase even after it has been usedfor a long time. In the description of the characteristics such asoptical anisotropy, the characteristics of the composition such as theoptical anisotropy and so forth are values measured in the methodsdisclosed in Examples. The first component includes one compound or twoor more compounds. “A ratio of the first component” means the percentageby weight (% by weight) of the first component based on the total weightof liquid crystal composition. A ratio of the second component and soforth are applied with the same rule. A ratio of an additive mixed withthe composition means the percentage by weight (% by weight) based onthe total weight of liquid crystal composition.

In the chemical formulas of the component compounds, symbol R¹ is usedin plural compounds. In these compounds, any two R¹ may be the same asor different from each other. In one case, for example, R¹ of thecompound (1) is ethyl and R¹ of the compound (1-1) is ethyl. In anothercase, R¹ of the compound (1) is ethyl and R¹ of the compound (1-1) ispropyl. This rule also applies to the symbols R², R³ and so forth. CL inthe chemical formulas is chlorine.

The invention has the following features.

1. The invention concerns a liquid crystal composition having a negativedielectric anisotropy that includes three components, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formula (1), the second component is at least onecompound selected from the group of compounds represented by formula(2), and the third component is at least one compound selected from thegroup of compounds represented by formula (3):

wherein R¹, R², R⁴, R⁵ and R⁶ are each independently alkyl having 1 to12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons or alkenyl having 2 to 12 carbons in which arbitrary hydrogen isreplaced by fluorine; R³ is alkenyl having 2 to 12 carbons; ring A, ringB and ring C are each independently 1,4-cyclohexylene or 1,4-phenylene;ring D and ring E are each independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene, or 2,5-difluoro-1,4-phenylene; Z¹and Z² are each independently a single bond, ethylene, methyleneoxy orcarbonyloxy; and m and n are each independently 1, 2 or 3; p and q areeach independently 0, 1, 2 or 3; and the sum of p and q is 3 or less.

2. The liquid crystal composition according to item 1, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formulas (1-1) to (1-4):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine; ring A¹, ring A², ring B¹ and ring B² are eachindependently 1,4-cyclohexylene or 1,4-phenylene; Z¹ and Z² are eachindependently a single bond, ethylene, methyleneoxy or carbonyloxy.

3. The liquid crystal composition according to item 2, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formula (1-1).

4. The liquid crystal composition according to item 2, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formula (1-3).

5. The liquid crystal composition according to any one of items 1 to 4,wherein the second component is at least one compound selected from thegroup of compounds represented by formulas (2-1) to (2-3):

wherein R³ is independently alkenyl having 2 to 12 carbons; R⁴ isindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine.

6. The liquid crystal composition according to item 5, wherein thesecond component is at least one compound selected from the group ofcompounds represented by formula (2-1).

7. The liquid crystal composition according to item 5, wherein thesecond component is at least one compound selected from the group ofcompounds represented by formula (2-2).

8. The liquid crystal composition according to item 5, wherein thesecond component is a mixture of at least one compound selected from thegroup of compounds represented by formula (2-1) and at least onecompound selected from the group of compounds represented by formula(2-2).

9. The liquid crystal composition according to any one of items 1 to 8,wherein the third component is a mixture of at least one compoundselected from the group of compounds represented by formula (3-1) to(3-10).

wherein R⁵ and R⁶ are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.

10. The liquid crystal composition according to item 9, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-1).

11. The liquid crystal composition according to item 9, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by formula (3-1) and at least onecompound selected from the group of compounds represented by formula(3-4).

12. The liquid crystal composition according to item 9, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by formula (3-1) and at least onecompound selected from the group of compounds represented by formula(3-6).

13. The liquid crystal composition according to item 9, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by formula (3-6) and at least onecompound selected from the group of compounds represented by formula(3-10).

14. The liquid crystal composition according to item 9, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by formula (3-1), at least one compoundselected from the group of compounds represented by formula (3-4) and atleast one compound selected from the group of compounds represented byformula (3-6).

15. The liquid crystal composition according to any one of items 1 to14, wherein a ratio of the first component is from 5% by weight to 35%by weight based on the total weight of the liquid crystal composition, aratio of the second component is from 20% by weight to 65% by weightbased on the total weight of the liquid crystal composition, and a ratioof the third component is from 25% by weight to 65% by weight based onthe total weight of the liquid crystal composition.

16. The liquid crystal composition according to any one of items 1 to15, wherein the composition has a maximum temperature of a nematic phaseof 70° C. or more, an optical anisotropy (25° C.) at a wavelength of 589nm of 0.08 or more, and a dielectric anisotropy (25° C.) at a frequencyof 1 kHz of −2 or less.

17. A liquid crystal display device that includes the liquid crystalcomposition according to any one of items 1 to 16.

18. The liquid crystal display device according to item 17 , wherein theliquid crystal display device has an operation mode of a VA mode, an IPSmode or a PSA mode, and has a driving mode of an active matrix mode.

The invention further includes: (1) the composition described above,wherein the composition further contains an optically active compound;(2) the composition described above, wherein the composition furthercontains an additive, such as an antioxidant, an ultraviolet lightabsorbent, an antifoaming agent, a polymerizable compound, apolymerization initiator and so forth; (3) an AM device containing thecomposition described above; (4) a device having a TN, ECB, OCB, IPS, VAor PSA mode, containing the composition described above; (5) a device ofa transmission type, containing the composition described above; (6) useof the composition described above as a composition having a nematicphase; and (7) use as an optically active composition by adding anoptically active compound to the composition described above.

The composition of the invention will be explained in the followingorder. First, the constitution of component compounds in the compositionwill be explained. Second, the main characteristics of the componentcompounds and the main effects of the compounds on the composition willbe explained. Third, combinations of components in the composition,desirable ratios of the component compounds and the basis thereof willbe explained. Fourth, a desirable embodiment of the component compoundswill be explained. Fifth, examples of the component compound will beshown. Sixth, additives that may be added to the composition will beexplained. Seventh, the preparation methods of the component compoundwill be explained. Lastly, use of the composition will be explained.

First, the constitution of component compounds in the composition willbe explained. The composition of the invention is classified into thecomposition A and the composition B. The composition A may furthercontain other compounds such as another liquid crystal compound, anadditive, an impurity, and so forth. “Another liquid crystal compound”is different from the compound (1), the compound (2), and the compound(3). Such a liquid crystal compound is mixed with the composition forthe purpose of adjusting the characteristics of the composition. Amongthe other liquid crystal compounds, an amount of a cyano compound isdesirably small from the viewpoint of stability to heat or ultravioletlight. The more desirable amount of a cyano compound is 0% by weight.The additive includes an optically active compound, an antioxidant, anultraviolet light absorbent, a coloring matter, an antifoaming agent, apolymerizable compound, a polymerization initiator and so forth. Theimpurity is a compound and so forth contaminated in the process such asthe synthesis of a component compound and so forth. Even when thecompound is a liquid crystal compound, it is classified into an impurityherein.

The composition B essentially consists of the compounds selected fromthe compound (1), the compound (2) and the compound (3). The term“essentially” means that the composition does not contain a liquidcrystal compound that is different from these compounds, except for theadditive and the impurity. The components of the composition B are fewerthan those of the composition A. The composition B is preferable to thecomposition A from the viewpoint of cost reduction. The composition A ispreferable to the composition B, because characteristics of thecomposition A can be further adjusted by mixing other liquid crystalcompounds.

Second, the main characteristics of the component compounds and the maineffects of the compounds on the composition will be explained. The maincharacteristics of the component compounds are summarized in Table 2. InTable 2, the symbol L represents large or high, the symbol M representsa middle degree, and the symbol S represents small or low. The symbolsL, M and S are classification based on qualitative comparison among thecomponent compounds.

TABLE 2 Characteristics of Compounds Compound (1) (2) (3) Maximumtemperature S-M S-M S-L Viscosity L M S-M Optical anisotropy M-L M-L S-LDielectric anisotropy L¹⁾ M-L¹⁾ 0 Specific resistance L L L ¹⁾The valueof dielectric anisotropy is negative, and the symbol indicates theabsolute value.

The main effects of the component compounds to the characteristics ofthe composition upon mixing the component compounds in the compositionare as follows. The compound (1) increases the absolute value of thedielectric anisotropy. The compound (2) increases the absolute value ofthe dielectric anisotropy and decreases the minimum temperature. Thecompound (3) increases the maximum temperature or decreases theviscosity.

Third, combinations of components in the composition, desirable ratiosof the component compounds and the basis thereof will be explained.Example of the combinations of the components in the composition isfirst component+second component+third component.

A desirable ratio of the first component is 5% by weight or more. forincreasing the absolute value of the dielectric anisotropy, and is 35%by weight or less for decreasing the minimum temperature. A moredesirable ratio is from 5% by weight to 30% by weight. A particularlydesirable ratio is from 5% by weight to 25% by weight.

A desirable ratio of the second component is 20% by weight or more forincreasing the absolute value of dielectric anisotropy and decreasingthe minimum temperature, and is 65% by weight or less for decreasing theviscosity. A more desirable ratio is from 20% by weight to 60% byweight. A particularly desirable ratio is from 25% by weight to 55% byweight.

A desirable ratio of the third component is 25% by weight or more forincreasing the maximum temperature, or decreasing the viscosity, and is65% by weight or less for increasing the absolute value of thedielectric anisotropy. A more desirable ratio is from 30% by weight to60% by weight. A particularly desirable ratio is from 35% by weight to55% by weight.

Fourth, a desirable embodiment of the component compound will beexplained. R¹, R², R³, R⁴, R⁵ and R⁶ are each independently alkyl having1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons or alkenyl having 2 to 12 carbons in which arbitrary hydrogen isreplaced by fluorine. Desirable R¹ and R² are each independently alkylhaving 1 to 12 carbons for increasing the stability to ultraviolet lightor heat. Desirable R⁴ is independently alkoxy having 1 to 12 carbons forincreasing the absolute value of the dielectric anisotropy. Desirable R⁵and R⁶ are each independently alkyl having 1 to 12 carbons forincreasing the stability to ultraviolet light or heat, or alkenyl having2 to 12 carbons for decreasing the minimum temperature. R³ is alkenylhaving 2 to 12 carbons.

Desirable alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,or octyl. More desirable alkyl is ethyl, propyl, butyl, pentyl or heptylfor decreasing a viscosity.

Desirable alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy, or heptyloxy. More desirable alkoxy is methoxy or ethoxy fordecreasing a viscosity.

Desirable alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, or 5-hexenyl. More desirablealkenyl is vinyl, 1-propenyl, 3-butenyl, or 3-pentenyl for decreasing aviscosity. A desirable configuration of —CH═CH— in these alkenyl dependson the position of a double bond. Trans is desirable in the alkenyl suchas 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyl, and3-hexenyl for decreasing the viscosity. Cis is desirable in the alkenylsuch as 2-butenyl, 2-pentenyl and 2-hexenyl. In these alkenyls, straightchained alkenyl is preferable to branched alkenyl.

Preferred examples of alkenyl in which arbitrary hydrogen is replaced byfluorine include 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and6,6-difluoro-5-hexenyl. More preferred examples thereof include2,2-difluorovinyl and 4,4-difluoro-3-butenyl for decreasing theviscosity.

Ring A, ring B and ring C are each independently 1,4-cyclohexylene, or1,4-phenylene, and when p is 2 or 3, two arbitrary rings A may be thesame as or different from each other. When q is 2 or 3, two arbitraryrings B may be the same as or different from each other, when m is 2 or3, two arbitrary rings C may be the same as or different from eachother. Desirable ring A, ring B and ring C are each independently1,4-cyclohexylene for decreasing the viscosity. Ring A¹, ring A², ringB¹ and ring B² are each independently 1,4-cyclohexylene,or1,4-phenylene. Desirable ring A¹, ring A², ring B¹ and ring B² are eachindependently 1,4-cyclohexylene for decreasing the viscosity. Ring D andE are each independently 1,4-cyclohexylene, or 1,4-phenylene,2-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene and when n is 2 or3, two arbitrary rings D may be the same as or different from eachother. When the rings are 2-fluoro-1,4-phenylene, the directions of therings are not limited. Desirable ring D and ring E are eachindependently 1,4-cyclohexylene for decreasing the viscosity, or1,4-phenylene for increasing the optical anisotropy.

Z¹ and Z² are each independently a single bond, ethylene, methyleneoxyor carbonyloxy, and when p, m and n are 2 or 3, two Z¹ may be the sameas or different from each other. When q is 2 or 3, two arbitrary Z² maybe the same as or different from each other. Desirable Z¹ is a singlebond for decreasing the viscosity, or methyleneoxy for increasing theabsolute value of dielectric anisotropy. Desirable Z² is a single bondfor decreasing a viscosity.

m and n are each independently 1, 2 or 3. Desirable m is 1 fordecreasing the minimum temperature. Desirable n is 1 for decreasing aviscosity.

p and q are each independently 0, 1, 2 or 3, and the sum of p and q is 3or less. Desirable p is 2 for increasing the maximum temperature.Desirable q is 0 for decreasing the minimum temperature.

Fifth, examples of the component compounds will be shown. In thedesirable compounds described below, R⁷ is independently straightchained alkyl having 1 to 12 carbons or straight chained alkoxy having 1to 12 carbons. R⁸ and R⁹ are each independently straight chained alkylhaving 1 to 12 carbons or straight chained alkenyl having 2 to 12carbons. R¹⁹ is independently straight chained alkenyl having 2 to 12carbons. In these desirable compounds, trans is preferable to cis forthe configuration of 1,4-cyclohexylene for increasing the maximumtemperature.

Desirable compounds (1) are the compounds (1-1-1) to (1-1-4), thecompounds (1-2-1) to (1-2-2), the compounds (1-3-1) to (1-3-5), and thecompounds (1-4-1) to (1-4-2). More desirable compounds (1) are thecompounds (1-1-1), the compounds (1-1-3), the compounds (1-3-1), thecompounds (1-3-3) and the compounds (1-4-1). Particularly desirablecompounds (1) are the compounds (1-1-3) and the compounds (1-3-3).Desirable compounds (2) are the compounds'(2-1-1) to compounds (2-3-1).More desirable compounds (2) are the compounds (2-1-1) and compounds(2-2-1). Desirable compounds (3) are the compounds (3-1-1) to compounds(3-10-1). More desirable compounds (3) are the compounds (3-1-1),compounds (3-3-1), compounds (3-4-1), and compounds (3-6-1)and compounds(3-10-1). Particularly desirable compounds (3) are compounds (3-1-1),compounds (3-4-1) and compounds (3-6-1).

Sixth, additives capable of being mixed with the composition will beexplained. The additives include an optically active compound, anantioxidant, an ultraviolet light absorbent, a coloring matter, anantifoaming agent, a polymerizable compound, a polymerization initiatorand so forth. An optically active compound is mixed in the compositionfor inducing a helical structure of liquid crystal to provide a twistangle. Examples of the optically active compound include the compounds(4-1) to (4-4) below. A desirable ratio of the optically active compoundis 5% by weight or less, and a more desirable ratio thereof ranges from0.01% by weight to 2% by weight.

An antioxidant is mixed with the composition in order to avoid adecrease in specific resistance caused by heating in the air or tomaintain a large voltage holding ratio at room temperature and alsonearly at the maximum temperature even after the device has been usedfor a long time.

Preferred examples of the antioxidant include the compound (5):

wherein n is an integer from 1 to 9. In the compound (5), desirable nare 1, 3, 5, 7, or 9. More desirable n are 1 or 7. When n is 1, thecompound (5) has a large volatility, and is effective in preventing thedecrease of specific resistance caused by heating in the air. When n is7, the compound (5) has a small volatility, and is effective inmaintaining a large voltage holding ratio at room temperature and alsonearly at the maximum temperature even after the device has been usedfor a long time. A desirable ratio of the antioxidant is 50 ppm or morein order to obtain the advantages thereof and is 600 ppm or less inorder to prevent the decrease of maximum temperature and to prevent theincrease of minimum temperature. A more desirable ratio is from 100 ppmto 300 ppm.

Preferred examples of the ultraviolet light absorbent include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer having steric hindrance such as an amineis also desirable. A desirable ratio of the absorbent and the stabilizeris 50 ppm or more for obtaining the advantages thereof and is 10,000 ppmor less for preventing the decreasing of maximum temperature andpreventing the increase of minimum temperature. A more desirable ratiothereof ranges from 100 ppm to 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition to suit for a device of a guest host (GH) mode. Adesirable ratio of the dye ranges from 0.01% by weight to 10% by weight.An antifoaming agent such as dimethyl silicone oil or methylphenylsilicone oil is mixed with the composition for preventing foaming fromoccurring. A desirable ratio of the antifoaming agent is 1 ppm or morefor obtaining the advantages thereof and is 1,000 ppm or less forpreventing display failure from occurring. A more desirable ratiothereof ranges from 1 ppm to 500 ppm.

A polymerizable compound is mixed with the composition for applying thecomposition to a device having a PSA (polymer sustained alignment) mode.Preferred examples of the polymerizable compound include compoundshaving a polymerizable group, such as acrylate, methacrylate, vinyl,vinyloxy, propenyl ether, vinylketone, epoxy such as oxirane, oxetane,and so forth. Particularly preferred examples thereof includederivatives of acrylate or methacrylate. A desirable ratio of thepolymerizable group is from 0.05% by weight or more for obtaining theadvantages thereof, and is 10% by weight or less for preventing displayfailure from occurring. A more desirable ratio is from 0.1% by weight to2% by weight. The polymerizable compound is polymerized preferably inthe presence of a suitable initiator, such as a photopolymerizationinitiator and so forth, under radiation of ultraviolet light. Suitableconditions for polymerization and a suitable type and a suitable amountof the initiator have been known by a skilled person in the art and aredisclosed in literatures. Examples of the photopolymerization initiatorsuitable for radical polymerization include Irgacure 651 (trade name),Irgacure 184 (trade name) and Darocure 1173 (trade name), all producedby Ciba Japan K.K. The polymerizable compound preferably contains aphotopolymerization initiator in an amount of from 0.1% by weight to 5%by weight, and particularly preferably contains a photopolymerizationinitiator in an amount of from 1% by weight to 3% by weight.

Seventh, the preparation methods of the component compounds will beexplained. These compounds can be prepared by known methods. Thepreparation method will be exemplified below. The compound (1-2-1) issynthesized by the method disclosed in JP 2005-35986 A. The compound(2-1-1) and compound (2-2-1) are synthesized by the method disclosed inJP H2-503441 A/1990. The compounds (3-1-1) and (3-4-1) are synthesizedby the method disclosed in JP H4-30382 A/1992. The antioxidant iscommercially available. The compound (5), wherein n is 1, is available,for example, from Sigma-Aldrich, Inc. The compound (5), wherein n is 7,and so forth are prepared by the method disclosed in U.S. Pat. No.3,660,505.

The compounds for which preparation methods were not described above canbe prepared according to the methods described in Organic Syntheses(John Wiley & Sons, Inc.), Organic Reactions (John Wiley & Sons, Inc.),Comprehensive Organic Synthesis (Pergamon Press), New ExperimentalChemistry Course (Shin Jikken Kagaku Kouza) (Maruzen, Inc.), and soforth. The composition is prepared according to known methods using thecompounds thus obtained. For example, the component compounds are mixedand dissolved in each other by heating.

Last, use of the composition will be explained. The compositions of theinvention mainly have a minimum temperature of −10° C. or less, amaximum temperature of 70° C. or more, and an optical anisotropy of 0.07to 0.20. The device containing the composition has a large voltageholding ratio. The composition is suitable for an AM device. Thecomposition is suitable especially for an AM device of a transmissiontype. The composition having an optical anisotropy of 0.08 to 0.25 andfurther having an optical anisotropy of 0.10 to 0.30 may be prepared bycontrolling ratios of the component compounds or by mixing other liquidcrystal compounds.

The composition can be used as a composition having a nematic phase andas an optically active composition by adding an optically activecompound.

The composition can be used for an AM device. It can be also used for aPM device. The composition can be also used for an AM device and a PMdevice having a mode such as PC, TN, STN, ECB, OCB, IPS, VA, PSA and soforth. It is desirable to use the composition for an AM device having aTN, OCB or IPS mode. These devices may be of a reflection type, atransmission type or a semi-transmission type. It is desirable to usethe composition for a device of a transmission type. It can be used foran amorphous silicon-TFT device or a polycrystal silicon-TFT device. Thecomposition is also usable for a nematic curvilinear aligned phase(NCAP) device prepared by microcapsulating the composition, and for apolymer dispersed (PD) device in which a three dimensional net-workpolymer is formed in the composition.

EXAMPLES

The invention will be described in more detail with reference toexamples below, but the invention is not construed as being limited tothe examples.

Sample of Liquid Crystal Compound for Measuring Characteristics:

A sample of the liquid crystal compound for measuring characteristicsincludes two cases, i.e., the case where the compound itself is used asa sample, and the case where the compound is mixed with mother liquidcrystals to prepare a sample.

In the later case where a sample is prepared by mixing the compound withmother liquid crystals, the measurement is carried out in the followingmanner. A sample was produced by mixing 15% by weight of the compoundand 85% by weight of mother liquid crystals. A value of characteristicsof the compound was calculated by extrapolating from a value obtained bymeasurement.

Extrapolated Value=(100×(measured value of sample)−(percentage by weightof mother liquid crystals)×(value measured for mother liquidcrystals))/(percentage by weight of liquid crystal compound)

In the case where a smectic phase was exhibited at 25° C. or crystalswere deposited at 25° C. at this ratio of the liquid crystal compoundand the mother liquid crystals, the ratio of the compound and the motherliquid crystals was changed step by step in the order of (10% byweight/90% by weight), (5% by weight/95% by weight), (1% by weight/99%by weight), respectively. The value of characteristics of the sample wasmeasured at a ratio where a smectic phase or crystals were not depositedat 25° C., and an extrapolated value was obtained by the aforementionedequation, which was designated as a value of characteristics of theliquid crystal compound.

While there are various kinds of mother liquid crystals for theaforementioned measurement, the composition of the mother liquidcrystals was as follows, for example.

Mother Liquid Crystals is:

17.2 wt %

27.6 wt %

20.7 wt %

20.7 wt %

13.8 wt %

Measurement of the characteristics was carried out according to thefollowing methods. Most methods are described in the Standard ofElectric Industries Association of Japan, EIAJ ED-2521 A or those withsome modifications.

Maximum Temperature of Nematic Phase (NI;):

A sample was placed on a hot plate in a melting point apparatus equippedwith a polarizing microscope, and while heating at the rate of 1° C. perminute, was observed with the polarizing microscope. A temperature wherea part of the sample is changed from a nematic phase to an isotropicliquid was measured. The maximum temperature of a nematic phase may beabbreviated to “a maximum temperature” in some cases.

Minimum Temperature of Nematic Phase (Tc; ° C.):

The glass bottles containing a sample having a nematic phase were storedin a freezer at 0° C., −10° C., −20° C., −30° C., −40° C. for aprescribed period of time. For example, a sample at −20° C. remains anematic phase. When a sample changes to crystal of smectic phase at −30°C., Tc is expressed as ≦−20° C. The minimum temperature of a nematicphase may be abbreviated to “a minimum temperature”.

Viscosity (η; Measured at 20° C.; mPa·s):

The viscosity was measured by means of an E-type viscometer.

Optical Anisotropy (refractive index anisotropy; Δn; measured at 25°C.):

Measurement was carried out with an Abbe refractometer mounting apolarizing plate on an ocular using a light at a wavelength of 589 nm.The surface of a main prism was rubbed in one direction, and then asample was dropped on the main prism. Refractive index (n∥) was measuredwhen the direction of a polarized light was parallel to that of therubbing. Refractive index (n⊥) was measured when the direction of apolarized light was perpendicular to that of the rubbing. A value ofoptical anisotropy was calculated from the equation: Δn=n|−n⊥.

Dielectric Anisotropy (Δε; Measured at 25° C.):

A value of a dielectric anisotropy was calculated from the equation:Δε=ε∥−ε⊥. A dielectric constant (ε∥) and a dielectric constant (ε⊥) wasmeasured by following method.

1) Measurement of dielectric constant (ε∥): A ethanol (20 mL) solutioncontaining octadecyltrimethoxysilane (0.16 mL) was coated on a glasssubstrate which have been cleaned well. After the glass substrate wasspun by a spinner, the glass substrate was heated at 150° C. in an hour.A sample was put in a VA device having a distance between two glasssubstrates (cell gap) of 4 μm, then the device was sealed with anadhesive which is cured by the irradiation of an ultraviolet light. Sinewaves (0.5 V, 1 kHz) were applied to the device, and a dielectricconstant (ε∥) in a major axis direction of a liquid crystal molecule wasmeasured after 2 seconds.

2) Measurement of dielectric constant (ε∥): A polyimide solution wascoated on a glass substrate which have been cleaned well. After theglass substrate was sintered, a rubbing process was performed on theobtained alignment film. A sample was put in a TN device having adistance between two glass substrates (cell gap) of 9 μm and a twistangle of 80° . Sine waves (0.5 V, 1 kHz) were applied to the device, anda dielectric constant (ε⊥) in a minor axis direction of a liquid crystalmolecule was measured after 2 seconds.

Threshold Voltage (Vth; Measured at 25° C.; V):

Measurement was carried out with an LCD Evaluation System Model LCD-5100made by Otsuka Electronics Co., Ltd. The light source was a halogenlamp. A sample was poured into a VA device of a normally black mode, andthe device was sealed with UV curable adhesive. Voltage to be applied tothe device (60 Hz, rectangular waves) was stepwise increased by 0.02Vstarting from 0V up to 20V. During the stepwise increasing, the devicewas irradiated with light in a perpendicular direction, and an amount ofthe light passing through the device was measured. Voltage-transmissioncurve was prepared, in which a maximum amount of a light corresponded to100% transmittance, and a minimum amount of a light corresponded to 0%transmittance. Threshold voltage is a value at 10% transmittance.

Voltage Holding Ratio (VHR-1; Measured at 25° C.; %):

A TN device used for measurement has a polyimide-alignment film and thecell gap between two glass substrates is 5 μm. A sample was poured intothe device, and then the device was sealed with an adhesive which ispolymerized by the irradiation of an ultraviolet light. The TN devicewas applied and charged with pulse voltage (60 microseconds at 5V).Decreasing voltage was measured for 16.7 milliseconds with High SpeedVoltmeter and the area A between a voltage curve and a horizontal axisin a unit cycle was obtained. The area B was an area without decreasing.Voltage holding ratio is a percentage of the area A to the area B.

Voltage Holding Ratio (VHR-2; Measured at 80° C.; %):

A TN device used for measurement has a polyimide-alignment film and thecell gap between two glass substrates is 5 μm. A sample was poured intothe device, and then the device was sealed with an adhesive which ispolymerized by the irradiation of an ultraviolet light. The TN devicewas applied and charged with pulse voltage (60 microseconds at 5V).Decreasing voltage was measured for 16.7 milliseconds with High SpeedVoltmeter and the area A between a voltage curve and a horizontal axisin a unit cycle was obtained. The area B was an area without decreasing.Voltage holding ratio is a percentage of the area A to the area B.

Voltage Holding Ratio (VHR-3; measured at 25° C.; %): A voltage holdingratio was measured after irradiating with ultraviolet light to evaluatestability to ultraviolet light. A composition having large VI-IR-3 has alarge stability to ultraviolet light. A TN device used for measurementhas a polyimide-alignment film and the cell gap is 5 μm. A sample waspoured into the device, and then the device was irradiated with lightfor 20 minutes. The light source was a super high voltage mercury lampUSH-500D (produced by Ushio, Inc.), and the distance between the deviceand the light source is 20 cm. In measurement of VHR-3, a decreasingvoltage is measured for 16.7 milliseconds. VHR-3 is desirably 90% ormore, and more desirably 95% or more.

Voltage Holding Ratio (VHR-4; Measured at 25° C.; %):

A voltage holding ratio was measured after heating a TN device having asample poured therein in a constant-temperature bath at 80° C. for 500hours to evaluate stability to heat. A composition having large VHR-4has a large stability to heat. In measurement of VHR-4, a decreasingvoltage is measured for 16.7 milliseconds.

Response Time (τ; Measured at 25° C. ; Millisecond):

Measurement was carried out with an LCD Evaluation System Model LCD-5100made by Otsuka Electronics Co., Ltd. Light source is a halogen lamp.Low-pass filter was set at 5 kHz. A sample was poured into a VA deviceof a normally black mode, in which a rubbing direction is anti-parallel.The device was sealed with UV curable adhesive, rectangle waves (60 Hz,10V, 0.5 seconds) were applied thereto. During application, the devicewas irradiated with light in a perpendicular direction, and an amount ofthe light passing through the device was measured. A maximum amount of alight corresponds to 100% transmittance, and a minimum amount of a lightcorresponds to 0% transmission. Fall time (τr ; millisecond) is a periodof time required for the change in transmittance from 90% to 10%.

Specific Resistance (ρ; Measured at 25° C.; Ωcm):

1.0 ml of a sample was charged in a vessel equipped with electrodes. Adirect current voltage of 10 V was applied to the vessel, and afterlapsing 10 second from the application of voltage, the direct electriccurrent was measured. The specific resistance was calculated by theequation:

(specific resistance)=((voltage)×(electric capacity of vessel))/((directcurrent)×(dielectric constant of vacuum)).

Gas Chromatographic Analysis:

A Gas Chromatograph Model GC-14B made by Shimadzu Corporation was usedfor measurement. The carrier gas was helium (2 milliliters per minute).The evaporator and the detector (FID) were set up at 280 ° C. and 300°C., respectively. A capillary column DB-1 (length 30 meters, bore 0.32millimeter, film thickness 0.25 μm, dimethylpolysiloxane as thestationary phase, non-polar) made by Agilent Technologies, Inc. was usedfor the separation of component compounds. After the column had beenkept at 200° C. for 2 minutes, it was further heated to 280° C. at therate of 5° C. per minute. A sample was dissolved in acetone (0.1% byweight) and 1 microliter of the solution was injected into theevaporator. A recorder used was a Model C-R5A Chromatopac Integratormade by Shimadzu Corporation or its equivalent. A gas chromatogramobtained showed the retention time of peaks and the peak areascorresponding to the component compounds.

Solvents for diluting the sample may also be chloroform, hexane, and soforth. The following capillary columns may also be used in order toseparate the component compounds: HP-1 made by Agilent Technologies Inc.(length 30 meters, bore 0.32 millimeter, film thickness 0.25 μm), Rtx-1made by Restek Corporation (length 30 meters, bore 0.32 millimeter, filmthickness 0.25 μm), and BP-1 made by SGE international Pty. Ltd. (length30 meters, bore 0.32 millimeter, film thickness 0.25 μm). A capillarycolumn CBPI-M50-025 (length 50 meters, bore 0.25 millimeter, filmthickness 0.25 μm) made by Shimadzu Corporation may also be used for thepurpose of avoiding an overlap of peaks of the compounds.

The ratio of the liquid crystal compound included in the composition maybe calculated according to the following method. The liquid crystalcompounds are detected by use of a gas chromatograph. The ratio of peakareas in the gas chromatogram corresponds to the ratio (in moles) of theliquid crystal compounds. When the capillary columns described above areused, the correction coefficient of respective liquid crystal compoundsmay be regarded as 1 (one). Accordingly, the ratio (% by weight) of theliquid crystal compound can be calculated from the ratio of peak areas.

The invention will be explained in detail by way of Examples. Theinvention is'not limited by the Examples described below. The compoundsdescribed in the Comparative Examples and the Examples are expressed bythe symbols according to the definition in Table 3. In Table 3, theconfiguration of 1,4-cyclohexylene is trans. The parenthesized numbernext to the symbolized compounds in the Examples corresponds to thenumber of the desirable compound. The symbol (−) means other liquidcrystal compound. A ratio (percentage) of a liquid crystal compound ispercentage by weight (% by weight) based on the total weight of liquidcrystal compounds, and the liquid crystal compositions further containimpurities. Last, the characteristics of the composition are summarized.

TABLE 3 Method of Description of Compound using Symbols R—(A₁)—Z₁— . . .—Z_(n)—(A_(n))—R′ 1) Left Terminal Group R— Symbol C_(n)H_(2n+1)— n-C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn- CH₂═CH— V-C_(n)H_(2n+1)—CH═CH— nV- CH₂═CH—C_(n)H_(2n)— Vn-C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn- CF₂═CH— VFF- CF₂═CH—C_(n)H_(2n)—VFFn- 2) Right Terminal Group —R′ Symbol —C_(n)H_(2n+1) -n—OC_(n)H_(2n+1) —On —CH═CH₂ -V —CH═CH—C_(n)H_(2n+1) -Vn—C_(n)H_(2n)—CH═CH₂ -nV —CH═CF₂ -VFF —F —F —Cl —CL —OCF₃ —OCF3 3)Bonding Group —Zn— Symbol —C₂H₄— 2 —COO— E —CH═CH— V —C≡C— T —CF₂O— X—CH₂O— 1O 4) Ring Structure —An— Symbol

H

B

B(F)

B(2F)

B(2F,3F)

B(2F,3Cl)

B(2Cl,3F)

B(2F,5F)

Cro(7F)

Cro(7F,8F) 5) Example of Description Example 1 V2-BB(F)B-1

Example 2 3-HB(2F,3F)-O2

Example 3 3-HHB-1

Example 4 5-HBB(F)B-3

Comparative Example 1

Example 4 was selected from the compositions disclosed in JP 2005-35986A. The basis is that the composition contains compounds (1-1-1) andcompounds (1-2-1), compounds (3-1-1) and compounds (3-2-1), and theviscosity is the smallest. The components and characteristics of thecomposition were as follows. The compositions. were prepared andmeasured according to the methods described above, because the responsetime at 25° C. was not described.

2-HCro(7F)-4 (—) 4% 3-HCro(7F,8F)-3 (1-1-1) 4% 2O-Cro(7F,8F)H-3 (1-2-1)4% 3-HH-4 (3-1-1) 5% 3-HH-5 (3-1-1) 5% 3-HH-O1 (3-1-1) 6% 3-HH-O3(3-1-1) 6% 3-HB-O1 (3-2-1) 5% 3-HB-O2 (3-2-1) 5% 3-HB(2F,3F)-O2 (—) 10%5-HB(2F,3F)-O2 (—) 10% 3-HHEH-3 (3) 4% 3-HHEH-5 (3) 3% 2-HHB(2F,3F)-1(—) 4% 3-HHB(2F,3F)-1 (—) 4% 3-HHB(2F,3F)-O2 (—) 12% 5-HHB(2F,3F)-O2 (—)9% NI = 70.0° C.; Δn = 0.077; η = 28.9 mPa · s; Δε = −4.2; τ = 12.6 ms.

Comparative Example 2

Example 1 was selected from the compositions, disclosed in JP2005-281560 A. The basis is that the composition contains compounds(1-1-3) and compounds (1-3-3), compounds (3-1-1) and compounds (3-4-1).The components and characteristics of the composition were as follows.The compositions were prepared and measured according to the methodsdescribed above, because the viscosity and the response time at 25° C.were not described.

3-H1OCro(7F,8F)-5 (1-1-3) 6% 5-H1OCro(7F,8F)-4 (1-1-3) 8%2-HH1OCro(7F,8F)-4 (1-3-3) 10% 2-HH1OCro(7F,8F)-5 (1-3-3) 10%3-HH1OCro(7F,8F)-5 (1-3-3) 5% 4-HH1OCro(7F,8F)-4 (1-3-3) 10% V-HH-5(3-1-1) 20% V2-HH-3 (3-1-1) 15% 3-HVH-3 (—) 11% V2-HHB-1 (3-4-1) 5% NI =84.0° C.; Δn = 0.068; η = 33.5 mPa · s; Δε = −3.2; τ = 14.0 ms.

Comparative Example 3

Example 3 was selected from the compositions disclosed in JP 2007-254583A. The basis is that the composition contains compounds (1-1-2) andcompounds (1-2-2), compounds (3-1-1) and compounds (3-2-1). Thecomponents and characteristics of the composition were as follows. Thecompositions were prepared and measured according to the methodsdescribed above, because the viscosity and the response time at 25° C.were not described.

3-H2Cro(7F,8F)-5 (1-1-2) 4% 2-Cro(7F,8F)2H-3 (1-2-2) 4% 3-HB(2F,3Cl)-O2(—) 15% 5-HB(2F,3Cl)-O2 (—) 15% 3-HHB(2F,3Cl)-O2 (—) 9% 5-HHB(2F,3Cl)-O2(—) 9% 3-HBB(2F,3Cl)-O2 (—) 9% 5-HBB(2F,3Cl)-O2 (—) 9% 2-HH-5 (3-1-1)11% 3-HH-4 (3-1-1) 12% 3-HB-O2 (3-2-1) 3% NI = 69.5° C.; Tc ≦ −20° C.; n= 0.084; η = 43.7 mPa · s; Δε = −3.5; τ = 18.3 ms.

Example 1

The compositions of Example 1 have a smaller viscosity and a shorterresponse time than those of Comparative Example 1.

3-HCro(7F,8F)-5 (1-1-1) 3% 2O-Cro(7F,8F)H-3 (1-2-1) 3% 3-HHCro(7F,8F)-5(1-3-1) 3% 2O-Cro(7F,8F)HH-5 (1-4-1) 3% V-HB(2F,3F)-O2 (2-1-1) 10% V-HHB(2F,3F)-O2 (2-2-1) 15% V2-HHB(2F,3F)-O2 (2-2-1) 15% V-HH-3 (3-1-1) 25%1V-HH-3 (3-1-1) 8% V-HHB-1 (3-4-1) 5% 2-BB(F)B-3 (3-6-1) 10% NI = 76.0°C.; Tc ≦ −20° C.; Δn = 0.091; η = 24.4 mPa · s; Δε = −3.1; Vth = 2.26 V;τ = 8.9 ms; VHR-1 = 99.0%; VHR-2 = 98.3%; VHR-3 = 98.1%.

Example 2

The compositions of Example 2 have a smaller viscosity and a shorterresponse time than those of Comparative Example 2.

3-H1OCro(7F,8F)-5 (1-1-3) 5% 5-H1OCro(7F,8F)-4 (1-1-3) 5%3-HH1OCro(7F,8F)-5 (1-3-3) 4% 5-HH1OCro(7F,8F)-5 (1-3-3) 6%3-BB1OCro(7F,8F)-5 (1-3) 5% V2-HB(2F,3F)-O2 (2-1-1) 15% V-HBB(2F,3F)-O2(2-3-1) 12% V-HH-3 (3-1-1) 27% 1V-HH-3 (3-1-1) 3% V2-HHB-1 (3-4-1) 10%3-BB(F)B-2V (3-6-1) 8% NI = 77.8° C.; Tc ≦ −20° C.; Δn = 0.109; η = 25.2mPa · s; Δε = −3.0; Vth = 2.31 V; τ = 9.2 ms; VHR-1 = 99.1%; VHR-2 =98.3%; VHR-3 = 98.2%.

Example 3

The compositions of Example3 have a smaller viscosity and a shorterresponse time than those of Comparative Example 3.

3-H2Cro(7F,8F)-5 (1-1-2) 5% 2-Cro(7F,8F)2H-3 (1-2-2) 5% V-HB(2F,3F)-O2(2-1-1) 10% V-HHB(2F,3F)-O2 (2-2-1) 10% 1V-HHB(2F,3F)-O2 (2-2-1) 5%1V2-HHB(2F,3F)-O2 (2-2-1) 5% V2-HBB(2F,3F)-O2 (2-3-1) 10% 3-HHEH-5 (3)3% 2-HH-3 (3-1-1) 22% 3-HH-O1 (3-1-1) 3% 7-HB-1 (3-2-1) 5% V-HHB-1(3-4-1) 7% V2-BB(F)B-1 (3-6-1) 5% 5-HBB(F)B-3 (3-10-1) 5% NI = 81.2° C.;Tc ≦ −20° C.; Δn = 0.098; η = 19.7 mPa · s; Δε = −2.7; Vth = 2.43 V; τ =7.7 ms; VHR-1 = 99.2%; VHR-2 = 98.0%; VHR-3 = 98.3%.

Example 4

3-BCro(7F,8F)-5 (1-1-4) 3% 3-HBCro(7F,8F)-5 (1-3-4) 4% V-HB(2F,3F)-O2(2-1-1) 11% V-HB(2F,3F)-O4 (2-1-1) 12% V-HHB(2F,3F)-O2 (2-2-1) 10%V-HHB(2F,3F)-O4 (2-2-1) 10% V-HH-3 (3-1-1) 25% V2-BB-1 (3-3-1) 6%1V-HBB-2 (3-5-1) 4% 5-HBBH-3 (3-8-1) 5% 3-HB(2F,3F)-O2 (—) 5%3-HBB(2F,3F)-O2 (—) 5% NI = 70.1° C.; Tc ≦ −20° C.; Δn = 0.98; η = 19.0mPa · s; Δε = −3.1; Vth = 2.21 V; τ = 7.5 ms; VHR-1 = 99.1%; VHR-2 =98.1%; VHR-3 = 98.1%.

Example 5

3-HH2Cro(7F,8F)-3 (1-3-2) 3% 3-HH2Cro(7F,8F)-5 (1-3-2) 4%3-Cro(7F,8F)2HH-5 (1-4-2) 3% V-HB(2F,3F)-O2 (2-1-1) 16% 1V-HB(2F,3F)-O4(2-1-1) 6% V-HHB(2F,3F)-O2 (2-2-1) 10% V2-HHB(2F,3F)-O2 (2-2-1) 7%V-HBB(2F,3F)-O2 (2-3-1) 10% V-HH-3 (3-1-1) 20% 1V-HH-3 (3-1-1) 7%5-HHEBH-3 (3-7-1) 4% 5-HB(F)BH-3 (3-9-1) 4% 3-H2B(2F,3F)-O2 (—) 3%3-HHB(2F,3F)-O2 (—) 3% NI = 90.1° C.; Tc ≦ −20° C.; Δn = 0.094; η = 22.8mPa · s; Δε = −3.6; Vth = 1.92 V; τ = 8.4 ms; VHR-1 = 99.0%; VHR-2 =98.1%; VHR-3 = 98.2%.

Example 6

3-HH1OCro(7F,8F)-5 (1-3-3) 8% V-HB(2F,3F)-O2 (2-1-1) 15% V-HB(2F,3F)-O4(2-1-1) 7% V-HBB(2F,3F)-O2 (2-3-1) 10% V2-HBB(2F,3F)-O2 (2-3-1) 10%2-HH-3 (3-1-1) 29% 3-HHB-1 (3-4-1) 6% 3-HHB-3 (3-4-1) 6% 3-HHB-O1(3-4-1) 6% 3-HBB(2F,3F)-O2 (—) 3% NI = 80.9° C.; Tc ≦ −20° C.; Δn =0.091; η = 20.9 mPa · s; Δε = −3.1; Vth = 2.26 V; τ = 7.8 ms; VHR-1 =99.2%; VHR-2 = 98.3%; VHR-3 = 98.2%.

Example 7

3-HH1OCro(7F,8F)-5 (1-3-3) 5% V-HB(2F,3F)-O2 (2-1-1) 10% V-HB(2F,3F)-O4(2-1-1) 10% 2-HH-3 (3-1-1) 25% 3-HH-4 (3-1-1) 5% 3-HB-O2 (3-2-1) 8%3-HHB-1 (3-4-1) 5% 3-HHB-3 (3-4-1) 6% 5-HBB-2 (3-5-1) 4% 3-HBB(2F,3F)-O2(—) 12% 4-HBB(2F,3F)-O2 (—) 10% NI = 71.6° C.; Tc ≦ −20° C.; Δn = 0.090;η = 20.2 mPa · s; Δε = −2.4; Vth = 2.35 V; τ = 7.7 ms; VHR-1 = 99.1%;VHR-2 = 98.1%; VHR-3 = 98.2%.

Example 8

3-HH1OCro(7F,8F)-5 (1-3-3) 5% V-HB(2F,3F)-O2 (2-1-1) 13% V-HB(2F,3F)-O4(2-1-1) 7% 2-HH-3 (3-1-1) 23% 3-HH-4 (3-1-1) 3% 3-HB-O2 (3-2-1) 6%5-HB-O2 (3-2-1) 5% 3-HHB-1 (3-4-1) 4% 3-HHB-3 (3-4-1) 5% 5-HBB-2 (3-5-1)3% 3-HBB(2F,3F)-O2 (—) 13% 4-HBB(2F,3F)-O2 (—) 7% 5-HBB(2F,3F)-O2 (—) 6%NI = 74.3° C.; Tc ≦ −20° C.; Δn = 0.093; η = 21.2 mPa · s; Δε = −2.9;Vth = 2.28 V; τ = 7.9 ms; VHR-1 = 99.2%; VHR-2 = 98.2%; VHR-3 = 98.2%.

Example 9

3-HH1OCro(7F,8F)-5 (1-3-3) 7% V-HB(2F,3F)-O2 (2-1-1) 15% V-HB(2F,3F)-O4(2-1-1) 12% 2-HH-3 (3-1-1) 24% 3-HH-4 (3-1-1) 6% 3-HHB-1 (3-4-1) 4%3-HHB-3 (3-4-1) 5% 5-HBB-2 (3-5-1) 3% 3-HHEBH-3 (3-7-1) 3% 3-HHEBH-5(3-7-1) 2% 3-HBB(2F,3F)-O2 (—) 13% 4-HBB(2F,3F)-O2 (—) 6% NI = 77.8° C.;Tc ≦ −20° C.; Δn = 0.087; η = 21.9 mPa · s; Δε = −3.1; Vth = 2.18 V; τ =8.0 ms; VHR-1 = 99.0%; VHR-2 = 98.1%; VHR-3 = 98.1%.

Example 10

3-HH1OCro(7F,8F)-5 (1-3-3) 5% V-HB(2F,3F)-O2 (2-1-1) 12% V-HB(2F,3F)-O4(2-1-1) 12% 2-HH-3 (3-1-1) 21% 3-HH-4 (3-1-1) 9% 3-HHB-1 (3-4-1) 6%3-HHB-3 (3-4-1) 6% 5-HBB-2 (3-5-1) 5% 3-HBB(2F,3F)-O2 (—) 12%4-HBB(2F,3F)-O2 (—) 6% 5-HBB(2F,3F)-O2 (—) 6% NI = 80.3° C.; Tc ≦ −20°C.; Δn = 0.092; η = 21.7 mPa · s; Δε = −2.9; Vth = 2.23 V; τ = 7.9 ms;VHR-1 = 99.3%; VHR-2 = 98.2%; VHR-3 = 98.2%.

Example 11

3-HH1OCro(7F,8F)-5 (1-3-3) 7% V-HB(2F,3F)-O2 (2-1-1) 14% V-HB(2F,3F)-O4(2-1-1) 12% 3-HHEH-5 (3) 3% 2-HH-3 (3-1-1) 24% 3-HH-O1 (3-1-1) 6%3-HHB-1 (3-4-1) 4% 3-HHB-3 (3-4-1) 5% 5-HBB-2 (3-5-1) 3% 5-HBB(F)B-2(3-10-1) 3% 3-HBB(2F,3F)-O2 (—) 13% 4-HBB(2F,3F)-O2 (—) 6% NI = 78.6°C.; Tc ≦ −20° C.; Δn = 0.089; η = 22.6 mPa · s; Δε = −3.0; Vth = 2.21 V;τ = 8.0 ms; VHR-1 = 99.2%; VHR-2 = 98.2%; VHR-3 = 98.1%.

The liquid crystal composition having a large optical anisotropy,negatively large dielectric anisotropy, a high stability to ultravioletlight contributes to a short response time, a large electric holdingratio, a large contrast ratio, and a long life of the device. Thesecharacteristics are desirable for an AM device used in a liquid crystalprojector, a liquid crystal television and so forth.

1. A liquid crystal composition having a negative dielectric anisotropy,comprising: a first component which is at least one compound selectedfrom the group of compounds represented by formula (1); a secondcomponent which is at least one compound selected from the group ofcompounds represented by formula (2); and a third component which is atleast one compound selected from the group of compounds represented byformula (3):

wherein R¹, R², R⁴, R⁵ and R⁶ are each independently alkyl having 1 to12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons or alkenyl having 2 to 12 carbons in which arbitrary hydrogen isreplaced by fluorine; R³ is alkenyl having 2 to 12 carbons; ring A, ringB and ring C are each independently 1,4-cyclohexylene or 1,4-phenylene;ring D and ring E are each independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene, or 2,5-difluoro-1,4-phenylene; Z¹and Z² are each independently a single bond, ethylene, methyleneoxy orcarbonyloxy; and m and n are each independently 1, 2 or 3; p and q areeach independently 0, 1, 2 or 3; and the sum of p and q is 3 or less. 2.The liquid crystal composition according to claim 1, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formulas (1-1) to (1-4):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine; ring A¹, ring A², ring B¹ and ring B² are eachindependently 1,4-cyclohexylene or 1,4-phenylene; Z¹ and Z² are eachindependently a single bond, ethylene, methyleneoxy or carbonyloxy. 3.The liquid crystal composition according to claim 2, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formula (1-1).
 4. The liquid crystal compositionaccording to claim 2, wherein the first component is at least onecompound selected from the group of compounds represented by formula(1-3).
 5. The liquid crystal composition according to claim 1, whereinthe second component is at least one compound selected from the group ofcompounds represented by formulas (2-1) to (2-3):

wherein R³ is independently alkenyl having 2 to 12 carbons; R⁴ isindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine.
 6. Theliquid crystal composition according to claim 5, wherein the secondcomponent is at least one compound selected from the group of compoundsrepresented by formula (2-1).
 7. The liquid crystal compositionaccording to claim 5, wherein the second component is at least onecompound selected from the group of compounds represented by formula(2-2).
 8. The liquid crystal composition according to claim 5, whereinthe second component is a mixture of at least one compound selected fromthe group of compounds represented by formula (2-1) and at least onecompound selected from the group of compounds represented by formula(2-2).
 9. The liquid crystal composition according to claim 1, whereinthe third component is a mixture of at least one compound selected fromthe group of compounds represented by formulas (3-1) to (3-10):

wherein R⁵ and R⁶ are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.
 10. The liquid crystal composition according to claim 9,wherein the third component is at least one compound selected from thegroup of compounds represented by formula (3-1)
 11. The liquid crystalcomposition according to claim 9, wherein the third component is amixture of at least one compound selected from the group of compoundsrepresented by formula (3-1) and at least one compound selected from thegroup of compounds represented by formula (3-4).
 12. The liquid crystalcomposition according to claim 9, wherein the third component is amixture of at least one compound selected from the group of compoundsrepresented by formula (3-1) and at least one compound selected from thegroup of compounds represented by formula (3-6).
 13. The liquid crystalcomposition according to claim 9, wherein the third component is amixture of at least one compound selected from the group of compoundsrepresented by formula (3-6) and at least one compound selected from thegroup of compounds represented by formula (3-10).
 14. The liquid crystalcomposition according to claim 9, wherein the third component is amixture of at least one compound selected from the group of compoundsrepresented by formula (3-1), at least one compound selected from thegroup of compounds represented by formula (3-4) and at least onecompound selected from the group of compounds represented by formula(3-6).
 15. The liquid crystal composition according to claim 1, whereina ratio of the first component is from 5% by weight to 35% by weightbased on the total weight of the liquid crystal composition, a ratio ofthe second component is from 20% by weight to 65% by weight based on thetotal weight of the liquid crystal composition, and a ratio of the thirdcomponent is from 25% by weight to 65% by weight based on the totalweight of the liquid crystal composition.
 16. The liquid crystalcomposition according to claim 1, wherein the composition has a maximumtemperature of a nematic phase of 70° C. or more, an optical anisotropy(25° C.) at a wavelength of 589 nm of 0.08 or more, and a dielectricanisotropy (25° C.) at a frequency of 1 kHz of −2 or less.
 17. A liquidcrystal display device that comprises the liquid crystal compositionaccording to claim
 1. 18. The liquid crystal display device according toclaim 17, wherein the liquid crystal display device has an operationmode of a VA mode, an IPS mode or a PSA mode, and has a driving mode ofan active matrix mode.